posted by sherry on .
a ball is dropped from a height of 10 meters.if the energy of the ball is reduced by 40% after striking the ground,how high can the ball bounce back?
It can bounce to 40% of the original height, or 4 meters in this case.
If the energy is reduced by 40%, then 60% is left. Therefore, PE = mgH = KE (at hitting the ground). Upward motion
0.6KE=0.6mgH = mgh. Then h=0.6x10=6 m.
Yes, I misread the question. 60% of the original height is correct
Mgh=k.e so the p. e=100x the 40% energy is reduced so we subtract the 40%of 100x=60xso height =60x/10=6m